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Re: [Xen-devel] [PATCH V2] xen: Check if the range is valid in init_domheap_pages

On 11/13/2013 01:26 PM, Jan Beulich wrote:
On 13.11.13 at 14:15, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
On ARM, when an initrd is given to xen by U-boot, it will reserve the memory
in the device tree.
In this case, when xen decides to free unused memory, dt_unreserved_regions
will call init_domheap_pages with the start and the end of range equals. But
the latter assumes that (start > end), if not Xen will hang because the
number of pages is equals to (unsigned)-1.

The change is simple enough, so I don't really mind it going in, but
I wonder ...

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>

     Changes in v2:
         - Change commit title
         - Move the check in init_domheap_pages

... who and why suggested to move it here. After all, I'm considering
it an error to call the function with non-page-aligned addresses and/
or end < start (I take it that page-aligned, but start == end is not a
problem without your change).

if ps == pe, then emfn == (smfn - 1). This will result to the number of pages of -1.

There is a similar check in init_xenheap_pages, it doesn't seem harmfull to let it here.

Julien Grall

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